One track in the MarlinTrkTracks collection (the one with omega = -3.19071e-05 ) has the following TrackState->getReferencePoints:
TrackState::AtLastHit : (1791.98, 319.048, -2273.11)
TrackState::AtCalorimeter: (-1847.35 -219.503 2335.41)

In this case, the AtCalorimeter one has been taken in the wrong direction along the helix.